The process in which the environment<span> selects </span>organisms<span> that will survive is called natural selection. It starts with overproduction; when an </span>organism<span> produces more offpsrings than can survive. The second is variation. Because there are so many offsprings, there will be variations.</span>
Answer:
<u>3) Uncontrolled cell division occurred as a result of gene mutations</u>
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Explanation:
Spontaneous modifications within the genome may occur during the process of cell division. When copies of the DNA inside the cell are made, these mutations cause errors; and can include small single nucleotide polymorphisms, and large scale additions or deletions across multiple genes.
Some, like somatic mutations, exist only inside vegetative (body) cells, that cannot be passed onto offspring. This is caused by several factors like
- UV radiation,
- chemical mutagens,
- infective agents
UV radiation damages strands of DNA, by causing dimers to form; here, consecutive nucleotide bases covalently bond instead of those on the complementary strand. This conformational change causes errors in DNA proofreading and repair mechanisms where bases are not well-incorporated into the strand- tumors (clumps of uncontrolled cell growth) may form, resulting in melanoma, a type of skin cancer.
Answer:
a. Decrease water reabsorption
: decrease blood pressure.
b. Decrease peripheral resistance
: decrease blood pressure
c. Vasodilation
: decrease blood pressure
d. Decrease salt intake
: decrease blood pressure
e. Decrease blood volume
: decrease blood pressure
f. Vasoconstriction
: increase blood pressure
g. Increase peripheral resistance: increase blood pressure
h. Increase salt intake: increase blood pressure
i. Increase blood volume
: increase blood pressure
j. Increase water reabsorption: increase blood pressure
Explanation:
- Total peripheral resistance: This term refers to the resistance offered by the vascular system to the blood flow. This resistance is a result of the friction between the blood and the vessel's walls. In other words, it is the opposition of the vessels to blood flow. The total peripheral resistance is the summary of all the bloody circuit resistances in the body. Those mechanisms that induce vasoconstriction conduce to an increase in total peripheral resistance, while mechanisms that induce vasodilation provoke a decrease in total peripheral resistance.
- Blood pressure: This term refers to the strength applied by the blood against the vessel walls as it flows. This pressure is determined by the bombed blood strength and the volume as well as by the vessel size and flexibility. Blood pressure changes continuously according to the activity, temperature, diet, emotional state, among others.
- Salt ingestion causes an increase in plasmatic osmolarity, stimulates thirst, and hence, water ingestion. Sodium retains water, expanding the blood volume and causing an increase in vessel pressure.
- The antidiuretic hormone, also known as vasopressin hormone, is released by changes in serum osmolarity or blood volume. Its function is to keep homeostasis and make kidneys conserve or keep water by concentrating urine and by reducing its volume. By these actions, the antidiuretic hormone stimulates water reabsorption, according to the organism´s needs.
- Kidneys control blood pressure in many ways. If the pressure is elevated, kidneys produce the loss of salt and water, normalizing arterial pressure. But if pressure is low, kidneys conserve water.
Circulatory system:
--The circulatory system is also known as the cardiovascular system.
-- It is composed of the heart, blood, blood vessels and also includes the lungs.
The primary function of the circulatory system to distribute oxygen, nutrients, hormones and other gases to cells of the other body systems. It delivers all the necessary components needed for all the cell activities. Without the circulatory system, we would not be alive.
It is our blood that carries these necessary nutrients, hormones, and oxygen. All these components trigger certain processes that keep other organs functioning. It also plays a role in eliminating waste by carrying them to the necessary organs that will filter them out. Without a way to dispose of waste, the body will eventually die.
